Fuel pump and purging system therefor



Jan. 16, 1968 v. D. RoosA 3,363,569

FUEL PUMP AND PURGING SYSTEM THEREFOR Filed Dec. 9, 1965 3 Sheets-Shee lVERNON D. ROOSA ATTQRMSYS Jan. 16, 1968 v` D. RoosA FUEL PUMP ANDPURGING SYSTEM THEREFOR 3 Sheets-sheet 2 Filed Dec. 9, 1965 mo TR m. V DWN O N R E V ATTORNEYS Jan. 1e, 196s' v. D. ROOSA 3,363,569

FUEL PUMP AND PURGING SYSTEM THEREFOR v Filed Deo. 9, 1965 'ssheets-sheet s "Il, Il

VENTOR. vf-:RN D, RQosA www4/M5730 ATTORN EYS United States Patent f3,363,569 FUEL PUMP AND PURGING SYSTEM THEREFOR Vernon D. Roosa, R0. Box1440, West Hartford, Comi. 06101 Filed Dec. 9, 1965, Ser. No. 513,153 11Claims. (Cl. 103-5) ABSTRACT F THE DISCLOSURE A fuel pump having a rotorwith low pressure transfer or feed pump on one end and a high pressurecharge pump on the other for the delivery of discrete charges of fuel tothe several cylinders of an associated engine wherein a conduitincluding a metering valve connects the outlet of the transfer pump tothe inlet of the charge pump, and a vortex air separator in the form ofa cone-shaped recess is provided in the conduit for the serial passageof fuel from the transfer pump and to the charge pump with the inlet tothe separa-tor being adjacent the larger diameter thereof and directingfuel tangentially into the separator and at an acute angle away from theapex thereof to receive fuel from the transfer pump, the separatorhaving an outlet adjacent its apex and an air vent ccmmunicating withthe central portion of its base.

The present invention relates to fuel pumps of the type utilized in fuelinjection systems for delivering measured charges of fuel to the nozzlesof an internal combustion engine and more particularly to the means forpurging air entrapped in the fuel therefrom.

A principal aim of this invention is to provide an automatic purgingarrangement for eliminating from the fuel any air which may be entrainedtherein.

Another object of this invention is to provide for the positivelubrication of the movable parts of the pump.

Other objects will be in part obvious and in part pointed out more indetail hereinafter.

The invention accordingly consists in the features of construction,combination of elements and arrangement of parts which will beexemplified in the construction hereafter set forth, and the scope ofthe application of which will be indicated in the appended claims.

In the drawings:

FIG. 1 is a longitudinal cross-sectional View7 partly roken away, of afuel injection pump embodying the present invention;

FIG. 2 is an enlarged fragmentary sectional view taken along the lines2-2 of FIG. l;

FIG. 3 is a fragmentary sectional view taken along the lines 3-3 of FiG.2; and

FIG. 4 is an enlarged cross-sectional view taken along the lines 4 4 ofFIG. l.

Referring now to the drawings in detail, in which like numerals refer tolike parts throughout the several figures, a pump exemplifying thepresent invention is of the type now commercially available forsupplying fuel charges to an associated internal combustion engine. Thepump comprises an external housing or casing having an axial bore oropening 12 rotatably supporting a pump rotor or distributor 14.

Y At the right end of the housing 10, as viewed in FIG. l, there ismounted a vane-type fuel supply or transfer pump 18 driven by the rotor14 and having an inlet port 16 and a discharge port 17. A diagonal inletpassage 20 delivers fuel to the transfer pump 1S from an inlet pipe 22which is connected to a fuel supply reservoir. The transfer pumpdelivers fuel under pressure through an outlet passage 24 in the housing10 to an air separator 26 from whence the fuel ows through a passage 28(FIG. 2)

Patented Jan. 16, 1968 ICC in the housing 10 to a longitudinal bore 30in the housing. A slideable spring biased pressure regulating value 32(FIG. 3) is mounted in the bore 30 for regulating the output pressure ofthe pump 18. Regulating valve 32 delivers fuel to the centrifugalmetering valve 34 at a pressure correlated with the speed of the drivingengine through conduit 33 and returns excess fuel to the transfer pumpinlet conduit 20 through conduit 35.

The high pressure charge pump generally denoted by the numeral 40 isformed by a transverse bore 42 in rotor 14 in which are slideablymounted a pair of opposed plungers 44. The outer ends of the plungersengage against shoes 46 which are slideably mounted in transversepassages 48 formed by the bifurcated end 47 of a separable drive shaft60 aligned with bore 42. As shown in FIG. 4, the bifurcated end of driveshaft 60 also provides a pair of flat opposed shoulders which engagescomplementary shoulders 45 on the rotor 14 to drive the same.

Surrounding the rotary member 14 is a generally circular or ring-likecam ring 50 preferably constructed of hardened steel which encircles therotor 14 in the plane of revolution of the plungers 44 and is mountedfor angular adjustment within an annular bore 49 in the pump housing.The cam has a plurality of pairs of diametrically opposed inwardlyextending cam lobes 52 which are adapted to actuate the plungers 44inwardly simultaneously for discharging fuel from the pump, it beingunderstood that the rollers 43 and the roller shoes 46 are disposedbetween the plungers 44 and the cam 50 whereby the rollers 43 act as camfollowers for translating the cam contour into this reciprocal movementof the plungers 44. The C-shaped ring 56 secured to the charge pump by ascrew fastener 5S (FIG. 4) provides an adjustable outer resilient topfor the roll shoes 46. A seal 62 is provided to prevent leakage of fuelinto or out of between the shaft 60 and the housing 10.

Upon rotation of the drive shaft 60, the transfer pump 1S and the chargepump 40 are rotated to supply measured charges of fuel under pressure toa plurality of fuel pump outlets 64- having suitable connections withthe fuel injection nozzles of an associated engine. During the outwardor intake stroke of the plungers 44 fuel is delivered to the charge pumpfrom the metering port 41 by a passage 66 in the housing 10 and adiagonal passage 68 in the rotor 14. During the inward or dischargestroke of the plungers 44 fuel is delivered under high pressure by anaxial passage 76 to a pressure-operated delivery valve 77 and agenerally radially extending distributor passage 73 adapted forsequential registration with a plurality of angularly spaced radialdelivery passages 63 in fluid communication respectively with aplurality of pump outlets 64, only one of which is shown for convenienceof illustration. It is to be noted that a one-way check valve 68aprevents reverse flow through inlet passage 68 during the dischargestroke of charge pump 40'.

The metering valve 34 may be adjusted in any suitable manner, and in theillustrated embodiment is shown as being a spool valve axiallyadjustable and rotatably driven by the centrifugal governor 31 againstthe force of spring 29, the bias of which may be adjusted or varied bylever 25. The governor 31 is provided with a gear 85 driven by gear 84secured to shaft 60. Inasmuch as the axial force of centrifugal governor31 is a function of engine speed, the position of the metering valve 34and hence the restriction offered by the metering port 41 due to theaxial shifting of the spool 34 will govern the engine at a speed whichmay be selected by varying the bias of the compression spring 29.

Referring now specifically to FIG. 4, there is shown a transverse borein the housing 10 in which an axially movable plunger 102 isreciprocably mounted. A passage 104 (FIG. 1) from the air separator 26is shown as being in communication with the bore 100 to deliverregulated transfer pump outlet pressure thereto, In the illustrateddesign, the plunger 102 includes a pilot valve 105 positioned in achamber 106, one end of which communicates with housing passage 104through passage 108 in plunger 102. A one-way valve is positioned inpilot valve 105 to prevent the reverse flow of fluid through the passageS as a result of intermittent pulsations of force imposed on the plunger102 due to the operation of the charge pump.

Pilot valve 105 is provided with an adjustable biasing spring 109 whichengages the end of a threaded adjusting screw 103 at the end oftransverse housing bore 100. Spring 109 opposes the transfer pump outletpressure acting on the right end of the pilot valve with the result thattransfer pump output pressure will urge the plunger 102 to the left, asseen in FIG. 2, against the bias of compression spring 109.

Pilot valve 105 is also provided with an annular land 110 which isaxially shiftable over port 111 in the plunger 102. Port 111communicates through passage 112 to a chamber 113 formed in the end oftransverse housing bore 100 to deliver fuel under pressure thereto whenannular land 110 of the pilot valve is moved to the left to providecommunication between passage 106 and port 111 via annulus 107 andpassage 112. inasmuch as the transfer pump pressure is a function ofengine speed, the balanced position assumed by the pilot valve isdetermined by the equilibrium between the forces imposed thereon by thetransfer pump pressure and spring. This, in turn, determines whether theport 111 communicates with annulus 112 to receive additional fuel fromthe transfer pump (and hence shift plunger 102 to the left to advancethe time of injection) or the port 111 communicates with passage 114 todump a portion of the fuel trapped in the chamber 113 into the pumphousing through passage 114 to permit the plunger 102 to move to theright. As shown in F1G. 4, the left end of annulus 107 is of reducedcross section to throttle the ow of fuel therethrough and stabilize theoperation ofthe pilot valve.

Since one end of the spring 109 engages stationary screw 103, it will beapparent that when the pilot valve is in equilibrium, the port 111 willbe automatically closed by land 110 as the plunger 102 moves to the leftby the increased fuel entering chamber 113.

For operatively connecting plunger 102 and cam 50, there is provided anarm 115 having a cylindrical body 116 mounted in a complementary radialbore 118 in the plunger 102. The connector 115 has an integral head 120closely received within a bore 101 of the cam ring 50 which serves as asocket therefor. The plunger 102 is recessed at 122 to receive a portionof the cam ring 50 extending within the bore 100, and the connector 115is preferably dimensioned to reciprocate with the plunger 102 within theperipheral confines of the bore 100. A snap ring 124 seated in anannular groove in the connector 115 prevents excess axial movement ofthe connector toward the cam ring.

A certain quantity of air is nearly always entrained in diesel fuel. Ifnot removed, such air results in the erratic operation of the fuel pumpand may prevent the pump from building up adequate pressure forsatisfactory performance, particularly during starting. In accordancewith this invention, means are provided for removing any air which maybe entrained in the fuel.

As shown in FlG, 1, the means provided includes an air separator 26which takes the form of an inverted cone, shown as having conical sidewalls with an included angle of about 30, disposed downstream of thetransfer pump 18 and upstream of the metering port 41 and charge pump 40to remove the air from the fuel prior to its passage into the meteringvalve and the charge pump. The passage 24, which delivers output fuelfrom transfer pump 18 to the air separator 25, has a restricted crosssection for a portion of its length at the end thereof whichcommunicates with the air separator 26. With this construction, thevelocity of the fuel entering into the air separator 26 is increased tospeed up the fuel as it whirls around the conical walls of the airseparator toward exit passage 20 thereby to improve the efficiency ofair separator 26 in separating the air from the liquid fuel.

As shown in F1G. 1, passage 24 communicates with the air separator 26 ata point adjacent the larger diameter thereof and in a manner so that thefuel enters the air separator in a direction substantially tangent tothe conical surface thereof. Preferably, the passage 24 is also disposedat an acute angle relative to the axis of the air separator 26 so as todirect the incoming fuel into the air separator 25 in a direction awayfrom the apex of the air separator to further improve the efficiencythereof by requiring the fuel to change its axial direction in passingthrough the air separator. Since the liquid fuel is heavier than theair, the air will be drawn toward the center of the whirling vortex andaway from the discharge passage 28 adjacent the apex of the separator.

A hollow plug 67 closes the base of the air separator 26 and is providedwith a radially directed passage 69 in which is loosely positioned awiggle wire 70 having a slight clearance with passage 69 to facilitatethe easy passage of air from the air separator 26 while impeding theflow of liquid fuel through the passage 69. Passage 69, in turn,communicates with a diagonal passage 71 in the housing 10 for deliveringthe removed air to the cavity in which charge pump 40 is positioned. Thepressure in the charge pump cavity and in the housing 10 may bemaintained at any suitable pressure, say, about 8 to l0 lbs. p.s.i., bya spring-biased dumpin valve 72 (FIG. 2) as hereinafter more fullydescribed and returns any excess fuel to the transfer pump inlet throughpassage 95. Since the output pressure of the transfer pump 13 issubstantially greater than the housing pressure as controlled by valve72, there is a continuous limited leakage of fuel through passage 69.

While the air separator 26 disposed upstream of the metering port 41 hasbeen found to be quite effective in removing any air entrained with theincoming fuel, there is also provided, in accordance with thisinvention, a further means for eliminating any air which may nd its wayinto annulus 51 of rotor 14, particularly after a period of idleness ofthe fuel pump.

Referring to FIGS` 1 and 2, there is provided at top dead center of bore12 of housing 10, an axial recess or V-shaped groove 51a having a heightof about l() mils and a 60 included angle which extends axially fromannulus 51 to the end of bore 12 of housing 10 to accommodate a smallconstant flow of metered fuel to the cavity containing the charge pump40. Since the recess 51:1 is positioned at top dead center, the air inthe annulus 51 will migrate to the vicinity of recess 51a to bedischarged from the annulus 51 into the cavity in which the charge pump40 is positioned.

As hereinbefore described, fuel is continuously discharged into thecavity of the char-ige pump 40 by passage 71 and groove 51a. Centrifugalforce resulting from the rotation of the shaft 60 and governor 31 willtend to concentrate such air at the centers of rotation hereof. Inaddition to the continuous flow of fuel into the charge pump cavity,additional means are provided to promote the positive How of fuel withinthe housing cavity to carry such trapped air out of the housing 10.

Referring specifically to FIG. 1, a passageway 81 in the shaft 60communicates with the bore thereof and with a port in a wall of thegovernor chamber 92 to provide for the positive ow of fuel therethrough.Fuel may also pass from the bore S2 past the rollers 43 of the chargepump and between the teeth 83 of step-up gears 84 and 35 which drive thegovernor 31 from the shaft 60. Fuel will flow radially inwardly oroutwardly through passageway 81 dependent upon whether the pressuregenerated by the rotation of the governor weights is greater than' thepressure imposed on the fuel within the passageway 8 1 due to therotation of drive shaft 6 0. In any event, there is a continuouspositive flow ef fuel through the center of the shaft as a result of thep ressure generated by the governor weights and by the continuous flowof fuel into the cavity of the charge pump 40 through passage 71 andV-shaped groove 51a'.

The centrifugal weights also cause a continuous positive flow of thefuel through the annulrclearanee 94 surrounding the governor cage 86 andthrough a plurality of stationary radial passages87 formed in the endwall of the governor chamber. The fuel then hows through a port 89 inthe end f governor cage 86 from whence it flows through an aperture 88in the thrustwasher 90 and past spider 99 thereby torequire circulationof fuel .adjacent the metering valve shaft 34 to prevent an air pocketat the center cf the thrust washer.

An annular clearance communicates with the goveri nor chamber 92 by arestricted annulus 93 which results from a difference in diameter of thepassageway 93 and the shaft of valve 34 by a difference in diameter ofthe order of 2/2- 4 mils. From the annular passage 91 the housing fuelflows to a passage 96 (see FIG. 2) which communicates with thedownstream side of the housing pressure relief valve 72.

A passage 98 between the end of the lowermost radial passage 87 on theend wall of the governor chamber (FIG. l) delivers fuel to the bore ofthe dumping valve 72 (FIG. 2) to maintain housing pressure and returnsexcess fuel to the pump inlet 22 through passage 95. Since the housingpressure is about 8-10 lbs. above the pressure in the passage 96, it isapparent that there will be a continuous return of a small amount offuel to the fuel reservoir. Since the restricted annulus is of such sizethat it readily passes air but offers resistance the ow of liquid fuel,the restriction is one which favors the passage of air from the governorchamber and thus minimizes the amount of fuel returned to the fuelreservoir.

From the foregoing, it is readily apparent that this invention providesfor the eliicient purging of air from the fuel entering the pump and forthe positive lubrication of the governor and the drive shaft coupling tothe rotor.

As will be apparent to persons skilled in the art, various modicationsand adaptations of the structure above described will become readilyapparent without departure from the spirit and scope of the invention,the scope of which is defined in the appended claims.

I claim:

1. A fuel pump comprising a housing having an inlet passage and outletpassages, a central bore in said housing, a fuel distributing rotorpositioned in said bore and having fuel inlet port means adapted tocommunicate with the inlet passage and having outlet port means adaptedto communicate in sequence during the rotation of said rotor with theoutlet passages of said housing to permit alternate admission anddischarge of fuel from the interior of the rotor, said fuel pump havinga low pressure transfer pump mounted on one end of the rotor, a chargepump mounted on the other end thereof, and a metering valve forcontrolling the output of the fuel pump, the improvement wherein conduitmeans are provided for delivering fuel from said transfer pump to saidcharge pump, and a vortex air separator is provided in said conduitmeans between said transfer pump and said charge pump, said airseparator comprising a cone shaped recess and having an inlet portadjacent its larger diameter to receive fuel from said transfer pump, afuel outlet port adjacent its apex for delivering purged fuel 7 to thecharge pump, and an air vent communicating with the central portion ofthe base of said recess.

2. A fuel purnp as recited in claim i where the inlet p asage to saidair separator is disposed so as to deliver the fuel therete in adirection susbtantially tangent with the conical surface thereof.

3. A fuel pur'np as recited in claim 1 wherein said inlet passage totheir ai'r separator delivers the fuel into said air separator at anacute angle with respect to the axis thereof and in a direction awayfrom the apex thereof.

4; A fuel pump as recited in claim 2 wherein the end portion of saidinletpassage is of reduced cross section to increase the velocity o ffuel entering the air separator.

5. A fuel pump as recited irl claim 1 wherein the fuel inlet port meansof said fuel distributing rotor includes an annulus for receiving fuelfrom said metering valve and means are provided for continuouslydischarging a limited amount of metered fuel from said annulus.

6. A fuel pump as recited in claim 5 wherein said dish charge means ispositioned at top dead center with respect to the said central here.

7. A fuel pump as recited in claim 6 wherein said discharge meanscomprises a generally axial groove formed in the surface of the centralbore of said housing.

8. A fuel pump comprising a housing containing fuel under pressure andhaving an inlet passage and outlet passages, a central bore in saidhousing, a fuel distributing rotor positioned in said bore and havingfuel inlet port means adapted to communicate with the inlet passage andhaving outlet port means adapted to communicate in sequence during therotation of said rotor with the outlet passages of said housing topermit alternate admission and discharge of fuel from the interior ofthe rotor, a low pressure transfer pump mounted on one end of the rotor,a charge pump mounted on the other end thereof, a metering valve forcontrolling the outlet of the fuel pump and a vortex air separatorupstream of said metering valve and said charge pump, a shaft having acentral cavity coupled to one end of said rotor to drive the same and acentrifugal governor for controlling said metering valve, theimprovement wherein conduit means are provided for connecting said shaftcavity with the governor chamber for the positive circulation of fuelthrough said shaft cavity, additional conduit means are provided for thepositive circulation of fuel through the governor chamber, and dischargemeans communicating between said governor chamber and the exterior ofthe pump housing are provided to eliminate any air otherwise confinedwithin the pump housing.

9. The fuel pump recited in claim 8 wherein said conduit means forcirculating fuel though the pump governor chamber includes stationaryradial grooves on an end Wall of the governor chamber.

10. The fuel pump as recited in claim 8 wherein said discharge meansincludes a restricted portion favoring the discharge of air over thedischarge of liquid fuel.

11. The fuel pump as recited in claim 8 wherein the centrifugal governorserves to pump the fuel through the shaft cavity and the governorchamber.

References Cited UNITED STATES PATENTS 2,641,238 6/1953 Roosa. 3,098,6047/ 1963 Dubberley 230-206 3,181,468 5/1965 Roosa. 3,186,513 6/1965 Dunnet al 103-111 3,215,079 11/1965 Roosa. 3,257,957 6/1966 Tracy 10S-1113,273,513 9/1966 Roper 103-42 o DONLEY I. STOCKING, Primary Examiner.

